At the risk of being labeled “snobby,” I normally never hold film adaptations of novels at too high a standard, nor do I throw a hissy fit when minor details are changed or omitted.

In Lynn Ramsay’s We Need to Talk About Kevin, a film version of Lionel Shriver’s 2002 novel, the omissions are almost impossible to ignore. Fans of the book will feel betrayed and those unfamiliar with the book will feel like they are watching an incomplete film.

We Need to Talk About Kevin tells the story of Eva (Tilda Swinton), a shaken mother dealing with the aftermath of her son Kevin’s brutal crime – murdering a handful of his classmates with a bow and arrow (substituted for the crossbow used in the novel). Kevin (Ezra Miller) is frighteningly unsympathetic and Eva, a once-prominent travel writer, has become a pariah in her small city.

The action in the novel unfolds through letters from Eva to her estranged husband Franklin. The film, on the other hand, jumps from timeline to timeline, giving no indication of where Franklin has disappeared to.

We see none of the deliciously tense in-prison conversations between Eva and Kevin, dialogues which made the novel tragic with a darkly funny twist.

This is just one of the many tonal choices which reflect Ramsay’s disregard for Shriver’s novel (Ramsey and Rory Kinnear contributed to the screenplay without input from Shriver). Though time restrictions are understandable, the film barely meets the 90-minute mark, and Ramsey and Kinnear left out a slew of important scenes.

While we do get the idea that even at a young age Kevin showed sociopathic tendencies, some key plot points are left out which offer far more context. A particularly poignant scene involves five-year-old Kevin coercing an eczema-ridden classmate to claw her flaky skin off, resulting in a literal bloodbath. Perhaps the scene was too disturbing for a film, but given the R rating, not much should have been sacrificed.

Another key plot point showed Kevin and a friend conspiring to frame a teacher at their high school for sexual assault – an incident which, in the novel, lead to Eva and Franklin’s separation.

Not only do these little left-out elements provide a lack of context for Kevin’s crimes, likening him to a suburban brat rather than a brilliant yet disturbed sociopath, they fail to properly set up Eva and Franklin’s separation.

Franklin, by the way, is portrayed by John C. Riley, a casting choice I was beyond excited about until the film went on to use him as a prop, and underuse Riley’s talents to an almost criminal degree.

Lack of loyalty aside, the film isn’t without other problems. In keeping with the recent trend of 90s alt-rockers composing chilling film scores, Radiohead’s Jonny Greenwood has contributed his composition talents to the film. His score fills are few and far between since most of the film is accompanied by cheesy, purposely unfitting 50s pop tunes (it becomes tiresome after half an hour), but when they do appear they seem dated, predictable and even cheap. It likens the film to an after-school special about violence.

The high-point of the film were the spectacular performances delivered by Tilda Swinton and Ezra Miller, made more impressive still given such limited material. The performance by Swinton certainly suggests an oversight on the part of the Academy this year.

The cinematography and editing is also brilliant, managing to capture beauty in dark moments while still creating a sense of unease.

Overall, the film is not horrible, but serves as a large disappointment for fans of the novel, and will undoubtedly feel ho-hum for those unfamiliar. Skip this one and read (or re-read) the book.